Shock absorbers are a common mechanical component in vehicles. For example, shock absorbers are found in cars, trucks, SUVs, semi-trucks, construction equipment, off-road vehicles and even industrial equipment. Shock absorbers are designed to dampen or reduce vertical motion of the vehicle when the wheels of the vehicle encounter a bump or a dip. In particular, shock absorbers dampen force, motion and energy between the passenger compartment of the vehicle and the wheels of the vehicle. Shock absorbers use pneumatic and/or hydraulic forces to reduce the speed at which the vehicle moves in a vertical direction in response to changing terrain, even when the wheels move toward or away from the vehicle. I.e., if a force tends to move the wheels toward the vehicle, such as a bump, the shock absorber dissipates the energy behind the force thus reducing the amplitude of the motion of the passenger compartment relative to the wheels.
However, shock absorbers suffer from a number of drawbacks. For example, the distance that the shock absorber can expand or stroke relative to its fully contracted length is limited in magnitude to a length that is less than the length of the shock body or compression chamber. I.e., the amount that one piston and shaft assembly can travel within its compression chamber. This is substantially less than its contracted length. In particular, a portion of the piston and shaft assembly must remain within the compression chamber, otherwise the attachment between the two is lost and the shock absorber is non-functional. I.e., there is a finite amount of space available in a vehicle suspension for the fully contracted length of a shock absorber, therefore prior art shocks absorbers are limited in expansion or stroke to a distance less than this finite space. Once this maximum is achieved, the connection between the wheels and the vehicle once more becomes a rigid connection, transmitting all motion to the passenger compartment.
In addition, shock absorbers generally utilize a single shaft. Thus, all of the force being transmitted through the wheels must be transmitted through this single shaft. This can lead to a great deal of wear on the shock absorbers. In fact, shock absorbers may wear out rather quickly in vehicles that tend to encounter rough terrain, such as off-road vehicles.
Accordingly, there is a need in the art for a shock absorber in which the distance between full contraction and full expansion or stroke is increased relative to the fully contracted length over conventional shock absorbers. In addition, there is a need in the art for the shock absorber to include multiple shafts.